1. Field of the Invention
The present invention relates to an automatic counting apparatus and method for automatically measuring the number of target objects included in an image. The present invention also relates to a recording medium on which a program for causing a computer to perform the method is recorded.
2. Description of the Related Art
A technique for discriminating individuals or attributes associated with the individuals, such as the gender, age, and the like from the face information included in an image to analyze the trend of the individuals or each of the attributes is known. U.S. Patent Application Publication No. 20030164878 and Japanese Unexamined Patent Publication No. 2004-348618, for example, disclose a method and system for analyzing the trend of the customers visiting sales floors of a store, in which the customers visiting the store are imaged by a camera installed in each corner of the store, and the face characteristic amounts of each customer is extracted from each recorded image to trace the customer, or to discriminate the gender or age of the customer.
Although, the technique for discriminating an individual or the gender based on the face information is advancing year after year, the technique is not yet fully matured to be able to discriminate 100% of any object. Generally speaking, there are two reasons why 100% discrimination rate is not achieved. First, there is a case that the face information is insufficient for discrimination. For example, only little information is extracted from the face of a person having long hair, in particular, from the side face of such person. Consequently, the discrimination rate for such persons is lower than that of the persons having short hair. Generally, it is said that the discrimination rate for females is lower than that of males since persons having long hair are found more often in females than males. The other reason is that there is a case that the characteristic of an individual is changed. For example, the facial characteristics of a female may be changed by the makeup so that the discrimination rate for females is lower than that of males. Further, the discrimination rate for the individuals wearing glasses is lower than that of the individuals without glasses, since the facial characteristic may be changed by changing the glasses. Still further, the discrimination rate for children is lower than that of adults since the facial expression may be changed as the children grow up.
In such cases described above, the discrimination rate (discrimination success rate) differs by 20% to 30% even if the same discrimination process is performed depending on the type of the object to be discriminated. In a statistical research, classified surveys according to the age and gender are often conducted as described in the aforementioned patent publications. The difference in the discrimination rate depending on the type of object to be surveyed gives a significant impact on the accuracy of surveys. In view of the problem described above, it is an object of the present invention to provide a scheme for minimizing the statistical error arising from the difference in the discrimination rate.